How online advertisers link your devices

With enough data and observations, online advertising firms are able to determine with a high degree of probability which devices belong to the same user.
Photo: Bloomberg

By analysing patterns in anonymous browsing data over time, internet advertising firms like Drawbridge can determine whether multiple computing devices belong to the same person.

■ An individual uses several devices to browse or shop on the internet. Some are at home and others at work, and the devices are not interconnected.

■ Each time any device is used to browse an advertising-enabled website, the device automatically records certain anonymous information, such as the date and time, location, web address visited, etc.

■ These anonymous reports, along with those from millions of other users, are automatically sent to an ad exchange, which forwards them to a company like Drawbridge for advertising or analysis.

AFR
AFR

■ Drawbridge searches the reports from this user and millions of others, looking for matches in websites visited, type of activity, device location, etc. With enough data and observations, Drawbridge is able to determine with a high degree of probability which devices belong to the same user. Drawbridge can than use the information it has gathered to direct targeted advertising to all devices belonging to the same user.